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Arquivos de Neuro-Psiquiatria

Print version ISSN 0004-282X

Arq. Neuro-Psiquiatr. vol.46 no.3 São Paulo Sept. 1988

http://dx.doi.org/10.1590/S0004-282X1988000300005 

Topografia y reactividad del potencial evocado visual

 

Topography and reactivity of the visual evoked potential

 

 

R. EtcheberrigarayI; F. LolasI; S. CamposanoI; D. ElguetaII

IUnidad de Psicofisiologia, Depto. de Fisiología y Biofísica (DFB), Fac. de Medicina, Universidad de Chile
IIAyudante-alumno del DFB

 

 


RESUMEN

El aumento - reducción (A-R) visual es evidente para las áreas centrales y exhibe diferencias hemisféricas. Este trabajo describe las características del potencial evocado visual (PEV) en derivaciones occipitales y su relación con A-R central: 16 sujetos de sexo masculino, diestros, jóvenes y sanos recibieron flashes de 10 us, frec de 1/s a intensidades de 0.36, 0.72 y 1.44 joules mediante estimulador Grass PS2. Se registró derivaciones Cz, C3, C4, Oz, O1 y 02 referidas a mastoides mediante electrodos subdérmicos. Un computador Nicolet CA-1000 promedió 100 respuestas para cada intensidad. Se midió latencia y amplitud peak to peak de los complejos P1N1 y N1P2 y se calculó pendiente intensidad/amplitud mediante regresión lineal. 10 sujetos tuvieron pendiente mayor que 0 en vertex (aumentadores) y 6 menor (reductores). P1N1 presenta reducción y asimetría hemisférica en Cz, que no se observa en Oz. Los aumentadores de N1P2 a nivel de Cz son reductores a nivel de, Oz y viceversa. Se discuten estos hallazgos en relación a las etapas en el procesamiento de la información visual y la significación funcional de los componentes del PEV.


SUMMARY

Augmenting/reducing (A/R) of visual evoked potentials (VEP) has been repeatedly observed in central derivations, with some subjects increasing, and others decreasing, VEP amplitude with increasing intensity of stimulation. Central derivations also exhibit hemispheric lateralization regarding A/R. This paper explores central and occipital VEP in the same population of 16 healthy, right-handed male subjects, stimulated with binocular light flashes 10 usec in duration delivered by a Grass PS2 stimulator at a rate of 1/sec and at the intensities of 0.36, 0.72 and 1.44 joules at source. Amplitudes and latencies of components P1, N1 and P2 agreed with those reported in the literature. On the basis of amplitude/intensity slope functions of «peak to peak» amplitudes (P1N1 and NIP2) at Cz, 10 augmenters (slope greater than 0) and 6 reducers (slope smaller than 0) were found. Compared to central leads (C3 and C4) occipital ones (O1 and 02) did not exhibit significant interhemispheric differences. Vertex augmenters for N1P2 were occipital reducers and vice-versa. The different characteristics of A/R at occipital and central leads are interpreted in terms of stages of visual information processing in primary and association areas and functional significance of VEP components.


 

 

Texto completo disponível apenas em PDF.

Full text available only in PDF format.

 

 

Agradecimientos - Financiado por Depto. de Investigación y Bibliotecas, Univ. de Chile y FONDECYT. El primer autor también agradece a la Fundación PUELMA.

 

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Unidad de Psicofisiologia - Casilla 10055 - Santiago 7 - Chile
NOTA - Artigo en homenage para el Dr. Oswaldo Lange (Dr. F. Lolas).

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